Table Of ContentTHE WONDERS OF LIGHT
Discover the spectacular power of light with this visually stunning celebration of the
multitude of ways in which light-based technologies are shaping our society.
Be inspired by state-of-the-art science
Sixteen beautiful, straightforward chapters demonstrate the science behind the fascinating
and surprising ways in which light can be harnessed and used, from displays, solar cells,
and the internet to advanced quantum technologies.
Be dazzled by brilliant color
Dramatic design and radiant color illustrations bring cutting-edge science and
ground-breaking innovations to life, clearly explaining the fundamental principles behind
them.
Be part of something bigger
Featuring a foreword by Nobel Laureate and former US Secretary of Energy, Steven Chu,
this book has been published in association with ICFO - The Institute of Photonic Sciences
to celebrate the 2015 International Year of Light. It will enthrall anyone interested in the
developments of science, technology and human civilization that have been made possible
by light.
Marta García-Matos is a physicist, mathematician and writer working at the outreach
division of ICFO - The Institute of Photonic Sciences.
Lluís Torner is the Founding Director of ICFO - The Institute of Photonic Sciences. He is
a Fellow of the European Physical Society, the European Optical Society, and the Optical
Society of America.
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© Institute of Photonic Sciences (ICFO) 2015
Graphic design: bpdisseny – Anna Jordà
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First published 2015
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THE WONDERS OF LIGHT
MARTA GARCÍA-MATOS
Institute of Photonic Sciences (ICFO)
LLUÍS TORNER
Institute of Photonic Sciences (ICFO)
contents
FOREWORD vi
ACkNOWLEDGMENTS ix
ABOUT ThE BOOk x
COLD 1
GENTLE 9
ShARp 17
FOCUS 25
ViRUS ATTACk 33
OpTOGENETiCS 41
FAST 49
RANDOM WALkS 57
DiSpLAyS 65
CONNECTED 73
pRiVACy 81
RiDDLES 89
NEW MATERiALS 97
CATCh ThAT ENERGy! 105
LiGhTiNG 113
SENSiNG 121
Foreword
Steven Chu
Stanford University
Nobel Laureate
Former US Secretary of Energy (2009–2013)
We are visual beings, and qualities such as “insight” and “vision” describe our
understanding well beyond sensory inputs. The ability to extend our sight beyond our eyes
gives deeper meaning to the observation of Yogi Berra, the great American philosopher of
the 20th century: “You see a lot by just watching.”
Visible light is a small sliver of a huge spectrum that includes radio waves with energies as
low as 2 x 10-13 eV (48 Hz) used to communicate with submarines, to cosmic gamma rays with
energies in excess of 300 GeV (7 x 1025 Hz). Maxwell’s equations, written in 1862, predicted
that radio waves, infrared radiation, and visible light are different forms of electromagnetic
waves. In the ensuing 150 years, we discovered X-rays and gamma rays, and subsequently
realized that these forms of energy are also part of the electromagnetic spectrum.
With the development of Quantum Mechanics in the 1920s, we discovered that the
energy of these waves cannot be dialed down arbitrarily, but there exists a fundamental
“graininess” to light: the photon. An electromagnetic wave of frequency ν is composed of
particles of light with energy E = ℏν, where Planck’s constant h is a universal constant of
min
Nature. Light can display both particle and wave properties. Remarkably, Maxwell’s
equations predicted that photons with energies less than 10-13 eV to greater than
3 x 10+11 eV all move at the same speed in vacuum. This prediction, yet to be contradicted
by experiment, is one of the wonders of light.
Marta García-Matos’ and Lluís Torner’s Wonders of Light presents a delightful
smorgasbord that illustrates how light continues to redefine our daily lives. The chapter
“Lighting” reminds us how artificial light liberated us from darkness (and boredom) and
protected us from predators; rapidly advancing technology is allowing us to create light
that mimics the changing hues of sunlight during the day. The chapter “Displays” shows
how light enhances our ability to visualize. All of these technologies rest on recent stunning
advances in the chapter “New Materials.”
Our ability to image the microscopic world down to the atomic level helps us
understand and combat “Virus Attacks.” The chapter “Focus” describes recent advances
in the effective resolution of optical microscopy that are able to circumvent the limits
imposed by the Uncertainty Principle of Quantum Mechanics. “Optogenetics” speaks of
powerful new ways of stimulating neurons in fully functioning animals that are leading to
a deeper understanding of the brain, and will soon find applications in pain control and
neuronal disorders.
Part of the wonder of light is that it can be used in applications that demand wildly
different properties. Light can be extremely “Sharp” for precise laser surgery and
destruction of selected cells. It can be “Gentle,” and used to cradle and move individual
cells and biomolecules. While intense beams of light can heat matter to temperatures that
mimic the center of the Sun, it can be used to create “Cold” more than a billion times colder
vi than the temperature of the most remote corners of our universe. Lasers can be utilized in
seemingly diametrically opposite applications. They can be ultra-stable clocks that detect a
deviation of less than one second over the lifetime of the universe or, alternatively, be used
to take ultra-“Fast” snapshots of changes in the electrons of atoms, molecules, and
materials. During this time, the atomic motion appears frozen. While a laser beam is
synonymous with a straight-line path, and more generally the path that minimizes the
transit time between two points in space and time, the chapter “Random Walks” introduces
the reader to the manner in which we exploit light when it travels in media that scatter and
absorb the photons.
Advances in science and technology do not require an intuitive understanding of the
underlying phenomena. The chapters “Privacy” and “Riddles” discuss applications of
quantum states connected to each other in ways far removed from human experience.
Nevertheless, we used Quantum Mechanics to invent the transistor, the laser, and more
recently, quantum computing and quantum cryptography. Over the past half a century, we
have learned to live in peaceful co-existence with a wildly successful theory that still defies
human intuition. “Connected” shows how we use light to transmit information at staggering
rates. While we routinely communicate with people half-way around the world in a blink of
an eye, we have no mechanical insight as to how light travels in vacuum. All that remains
of the mechanical model Maxwell used to arrive at his equations are the equations: like the
Cheshire Cat in Alice in Wonderland, the body of the cat disappears and all that remains is
its smile. Massive particles, electrons, atoms, molecules also have wave-like properties, but
today there is a debate as to whether the quantum phase frequency ν, given by
E = mc2 = ℏν, that appears in our most general theory of Quantum Mechanics is
measurable in principle.
The Wonders of Light also discusses how light will help us transition to a sustainable
world. Because of our ability to exploit fossil energy, a growing number of people keep their
homes warm in the winter, cool in the summer, and lit at night. Many of us go to the local
market in cars with the power of over a hundred horses and fly across continents in wide-
body airplanes with the power of a hundred thousand horses. The Sun is ultimately the
source of this energy. What took Nature hundreds of millions of years to create in coal, oil,
and natural gas, we are using up in hundreds of years.
Long before we run out of fossil fuels, there is another danger. The carbon emissions
used to generate the equivalent of more than a billion horses working continuously have
created significant climate-change risks. The overwhelming consensus among climate
scientists is that the Earth is warming up due to the burning of fossil fuels, and we need
to drastically reduce carbon emissions by mid-century. To accomplish this task, we must
convert massive amounts of sunlight energy into electricity. The chapter “Catch that
Energy!” describes how the technology is racing ahead. A wonder and necessity of light is
its role in providing a clean source of energy necessary to protect us from dire peril. vii
